Radar and object detection method

Abstract

A DS-SS radar 10 detects an object in such a way that a code generator 21, an oscillator 32, and an antenna 24 repeatedly send a sending signal modulated with a predetermined-frequency code generated by the code generator 21, an A/D converter 45 samples the code, included in the reflected wave of the sending signal reflected by an object, with a sampling period lower than the period of the code, and a correlator 46 calculates the correlation between the reference code, generated by re-arranging the code from the code generator 21 at an interval of Nsp, and the sampling data converted by the A/D converter 45.

The invention claimed is: 
     
       1. A radar comprising:
 a sender that has a code generator and repeatedly sends a sending signal modulated by a code generated by the code generator, the code having a predetermined period; 
 a receiver that samples a reflected wave of the sending signal, reflected by an object, with a sampling period lower than the predetermined period; and 
 a detector that detects the object by calculating a correlation between re-arranged data and the reflected wave sampled by the receiver, the re-arranged data corresponding to data generated by re-arranging the code, generated by the code generator, at an interval corresponding to the sampling period, wherein 
 the code is an M sequence code, and 
 the sampling period is a period calculated by multiplying Nsp by a width of one chip of the code, Nsp being a number that is smaller than a code length N of the code and is a power of 2. 
 
     
     
       2. The radar according to  claim 1 , wherein
 the detector outputs data generated by further re-arranging correlation output data at an interval of (N+1)/Nsp, the correlation output data being acquired by calculating the correlation between the re-arranged data and the reflected wave. 
 
     
     
       3. The radar according to  claim 1 , further comprising a reference code generator that is separate from the code generator wherein
 the reference code generator generates the re-arranged data corresponding to data generated by re-arranging the code, generated by the code generator, at the interval corresponding to the sampling period and 
 the detector detects the object by calculating a correlation between the re-arranged data, generated by the reference code generator, and the reflected wave sampled by the receiver. 
 
     
     
       4. An object detection method comprising:
 a sending step of repeatedly sending a sending signal modulated by a code generated by a code generator, the code having a predetermined period; 
 a reception step of sampling a reflected wave of the sending signal, reflected by an object, with a sampling period lower than the predetermined period; and 
 a detection step of detecting the object by calculating a correlation between re-arranged data and the reflected wave sampled in the reception step, the re-arranged data corresponding to data generated by re-arranging the code, generated by the code generator, at an interval corresponding to the sampling period, wherein 
 the code is an M sequence code, and 
 the sampling period is a period calculated by multiplying Nsp by a width of one chip of the code, Nsp being a number that is smaller than a code length N of the code and is a power of 2. 
 
     
     
       5. The object detection method according to  claim 4  wherein
 in the detection step, data generated by further re-arranging correlation output data at an interval of (N+1)/Nsp is output, the correlation output data being acquired by calculating the correlation between the re-arranged data and the reflected wave. 
 
     
     
       6. The object detection method according to  claim 4 , further comprising a reference code generation step of generating from a reference code generator the re-arranged data corresponding to data generated by re-arranging the code, generated by the code generator, at an interval corresponding to the sampling period, the reference code generator being separate from the code generator wherein
 in the detection step, the object is detected by calculating a correlation between the re-arranged data, generated in the reference code generation step, and the reflected wave sampled in the reception step.